// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
#define V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_

#include "src/label.h"
#include "src/regexp/regexp-ast.h"

namespace v8 {
namespace internal {

    static const uc32 kLeadSurrogateStart = 0xd800;
    static const uc32 kLeadSurrogateEnd = 0xdbff;
    static const uc32 kTrailSurrogateStart = 0xdc00;
    static const uc32 kTrailSurrogateEnd = 0xdfff;
    static const uc32 kNonBmpStart = 0x10000;
    static const uc32 kNonBmpEnd = 0x10ffff;

    struct DisjunctDecisionRow {
        RegExpCharacterClass cc;
        Label* on_match;
    };

    class RegExpMacroAssembler {
    public:
        // The implementation must be able to handle at least:
        static const int kMaxRegister = (1 << 16) - 1;
        static const int kMaxCPOffset = (1 << 15) - 1;
        static const int kMinCPOffset = -(1 << 15);

        static const int kTableSizeBits = 7;
        static const int kTableSize = 1 << kTableSizeBits;
        static const int kTableMask = kTableSize - 1;

        enum IrregexpImplementation {
            kIA32Implementation,
            kARMImplementation,
            kARM64Implementation,
            kMIPSImplementation,
            kS390Implementation,
            kPPCImplementation,
            kX64Implementation,
            kX87Implementation,
            kBytecodeImplementation
        };

        enum StackCheckFlag {
            kNoStackLimitCheck = false,
            kCheckStackLimit = true
        };

        RegExpMacroAssembler(Isolate* isolate, Zone* zone);
        virtual ~RegExpMacroAssembler();
        // This function is called when code generation is aborted, so that
        // the assembler could clean up internal data structures.
        virtual void AbortedCodeGeneration() { }
        // The maximal number of pushes between stack checks. Users must supply
        // kCheckStackLimit flag to push operations (instead of kNoStackLimitCheck)
        // at least once for every stack_limit() pushes that are executed.
        virtual int stack_limit_slack() = 0;
        virtual bool CanReadUnaligned() = 0;
        virtual void AdvanceCurrentPosition(int by) = 0; // Signed cp change.
        virtual void AdvanceRegister(int reg, int by) = 0; // r[reg] += by.
        // Continues execution from the position pushed on the top of the backtrack
        // stack by an earlier PushBacktrack(Label*).
        virtual void Backtrack() = 0;
        virtual void Bind(Label* label) = 0;
        virtual void CheckAtStart(Label* on_at_start) = 0;
        // Dispatch after looking the current character up in a 2-bits-per-entry
        // map.  The destinations vector has up to 4 labels.
        virtual void CheckCharacter(unsigned c, Label* on_equal) = 0;
        // Bitwise and the current character with the given constant and then
        // check for a match with c.
        virtual void CheckCharacterAfterAnd(unsigned c,
            unsigned and_with,
            Label* on_equal)
            = 0;
        virtual void CheckCharacterGT(uc16 limit, Label* on_greater) = 0;
        virtual void CheckCharacterLT(uc16 limit, Label* on_less) = 0;
        virtual void CheckGreedyLoop(Label* on_tos_equals_current_position) = 0;
        virtual void CheckNotAtStart(int cp_offset, Label* on_not_at_start) = 0;
        virtual void CheckNotBackReference(int start_reg, bool read_backward,
            Label* on_no_match)
            = 0;
        virtual void CheckNotBackReferenceIgnoreCase(int start_reg,
            bool read_backward, bool unicode,
            Label* on_no_match)
            = 0;
        // Check the current character for a match with a literal character.  If we
        // fail to match then goto the on_failure label.  End of input always
        // matches.  If the label is nullptr then we should pop a backtrack address
        // off the stack and go to that.
        virtual void CheckNotCharacter(unsigned c, Label* on_not_equal) = 0;
        virtual void CheckNotCharacterAfterAnd(unsigned c,
            unsigned and_with,
            Label* on_not_equal)
            = 0;
        // Subtract a constant from the current character, then and with the given
        // constant and then check for a match with c.
        virtual void CheckNotCharacterAfterMinusAnd(uc16 c,
            uc16 minus,
            uc16 and_with,
            Label* on_not_equal)
            = 0;
        virtual void CheckCharacterInRange(uc16 from,
            uc16 to, // Both inclusive.
            Label* on_in_range)
            = 0;
        virtual void CheckCharacterNotInRange(uc16 from,
            uc16 to, // Both inclusive.
            Label* on_not_in_range)
            = 0;

        // The current character (modulus the kTableSize) is looked up in the byte
        // array, and if the found byte is non-zero, we jump to the on_bit_set label.
        virtual void CheckBitInTable(Handle<ByteArray> table, Label* on_bit_set) = 0;

        // Checks whether the given offset from the current position is before
        // the end of the string.  May overwrite the current character.
        virtual void CheckPosition(int cp_offset, Label* on_outside_input);
        // Check whether a standard/default character class matches the current
        // character. Returns false if the type of special character class does
        // not have custom support.
        // May clobber the current loaded character.
        virtual bool CheckSpecialCharacterClass(uc16 type, Label* on_no_match);
        virtual void Fail() = 0;
        virtual Handle<HeapObject> GetCode(Handle<String> source) = 0;
        virtual void GoTo(Label* label) = 0;
        // Check whether a register is >= a given constant and go to a label if it
        // is.  Backtracks instead if the label is nullptr.
        virtual void IfRegisterGE(int reg, int comparand, Label* if_ge) = 0;
        // Check whether a register is < a given constant and go to a label if it is.
        // Backtracks instead if the label is nullptr.
        virtual void IfRegisterLT(int reg, int comparand, Label* if_lt) = 0;
        // Check whether a register is == to the current position and go to a
        // label if it is.
        virtual void IfRegisterEqPos(int reg, Label* if_eq) = 0;
        virtual IrregexpImplementation Implementation() = 0;
        virtual void LoadCurrentCharacter(int cp_offset,
            Label* on_end_of_input,
            bool check_bounds = true,
            int characters = 1)
            = 0;
        virtual void PopCurrentPosition() = 0;
        virtual void PopRegister(int register_index) = 0;
        // Pushes the label on the backtrack stack, so that a following Backtrack
        // will go to this label. Always checks the backtrack stack limit.
        virtual void PushBacktrack(Label* label) = 0;
        virtual void PushCurrentPosition() = 0;
        virtual void PushRegister(int register_index,
            StackCheckFlag check_stack_limit)
            = 0;
        virtual void ReadCurrentPositionFromRegister(int reg) = 0;
        virtual void ReadStackPointerFromRegister(int reg) = 0;
        virtual void SetCurrentPositionFromEnd(int by) = 0;
        virtual void SetRegister(int register_index, int to) = 0;
        // Return whether the matching (with a global regexp) will be restarted.
        virtual bool Succeed() = 0;
        virtual void WriteCurrentPositionToRegister(int reg, int cp_offset) = 0;
        virtual void ClearRegisters(int reg_from, int reg_to) = 0;
        virtual void WriteStackPointerToRegister(int reg) = 0;

        // Compares two-byte strings case insensitively.
        // Called from generated RegExp code.
        static int CaseInsensitiveCompareUC16(Address byte_offset1,
            Address byte_offset2,
            size_t byte_length, Isolate* isolate);

        // Check that we are not in the middle of a surrogate pair.
        void CheckNotInSurrogatePair(int cp_offset, Label* on_failure);

        // Controls the generation of large inlined constants in the code.
        void set_slow_safe(bool ssc) { slow_safe_compiler_ = ssc; }
        bool slow_safe() { return slow_safe_compiler_; }

        enum GlobalMode {
            NOT_GLOBAL,
            GLOBAL_NO_ZERO_LENGTH_CHECK,
            GLOBAL,
            GLOBAL_UNICODE
        };
        // Set whether the regular expression has the global flag.  Exiting due to
        // a failure in a global regexp may still mean success overall.
        inline void set_global_mode(GlobalMode mode) { global_mode_ = mode; }
        inline bool global() { return global_mode_ != NOT_GLOBAL; }
        inline bool global_with_zero_length_check()
        {
            return global_mode_ == GLOBAL || global_mode_ == GLOBAL_UNICODE;
        }
        inline bool global_unicode() { return global_mode_ == GLOBAL_UNICODE; }

        Isolate* isolate() const { return isolate_; }
        Zone* zone() const { return zone_; }

    private:
        bool slow_safe_compiler_;
        GlobalMode global_mode_;
        Isolate* isolate_;
        Zone* zone_;
    };

    class NativeRegExpMacroAssembler : public RegExpMacroAssembler {
    public:
        // Type of input string to generate code for.
        enum Mode { LATIN1 = 1,
            UC16 = 2 };

        // Result of calling generated native RegExp code.
        // RETRY: Something significant changed during execution, and the matching
        //        should be retried from scratch.
        // EXCEPTION: Something failed during execution. If no exception has been
        //        thrown, it's an internal out-of-memory, and the caller should
        //        throw the exception.
        // FAILURE: Matching failed.
        // SUCCESS: Matching succeeded, and the output array has been filled with
        //        capture positions.
        enum Result { RETRY = -2,
            EXCEPTION = -1,
            FAILURE = 0,
            SUCCESS = 1 };

        NativeRegExpMacroAssembler(Isolate* isolate, Zone* zone);
        ~NativeRegExpMacroAssembler() override;
        bool CanReadUnaligned() override;

        // Returns a {Result} sentinel, or the number of successful matches.
        static int Match(Handle<Code> regexp, Handle<String> subject,
            int* offsets_vector, int offsets_vector_length,
            int previous_index, Isolate* isolate);

        // Called from RegExp if the backtrack stack limit is hit.
        // Tries to expand the stack. Returns the new stack-pointer if
        // successful, and updates the stack_top address, or returns 0 if unable
        // to grow the stack.
        // This function must not trigger a garbage collection.
        static Address GrowStack(Address stack_pointer, Address* stack_top,
            Isolate* isolate);

        static const byte* StringCharacterPosition(
            String subject, int start_index, const DisallowHeapAllocation& no_gc);

        static int CheckStackGuardState(Isolate* isolate, int start_index,
            bool is_direct_call, Address* return_address,
            Code re_code, Address* subject,
            const byte** input_start,
            const byte** input_end);

        // Byte map of one byte characters with a 0xff if the character is a word
        // character (digit, letter or underscore) and 0x00 otherwise.
        // Used by generated RegExp code.
        static const byte word_character_map[256];

        static Address word_character_map_address()
        {
            return reinterpret_cast<Address>(&word_character_map[0]);
        }

        // Returns a {Result} sentinel, or the number of successful matches.
        V8_EXPORT_PRIVATE static int Execute(Code code, String input,
            int start_offset,
            const byte* input_start,
            const byte* input_end, int* output,
            int output_size, Isolate* isolate);
    };

} // namespace internal
} // namespace v8

#endif // V8_REGEXP_REGEXP_MACRO_ASSEMBLER_H_
